(1) Field of the Invention
This invention relates to a substrate treating apparatus for treating semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for organic EL devices, substrates for FEDs (Field Emission Displays), substrates for optical displays, substrates for magnetic disks, substrates for magnetic optical disks, substrates for photomasks or substrates for solar cells (hereinafter called simply substrates). The apparatus takes in the substrates along with pods thereof, takes the substrates out of the pods, carries out various types of treatment such as cleaning treatment and etching treatment for the substrates, and puts the substrates back into the pods for delivery.
(2) Description of the Related Art
Conventionally, a first apparatus of this type includes a substrate treating unit, a pod storage and transport unit and a load port. The pod storage and transport unit has a plurality of racks, an internal receiver, a first transport device and a second transport device (see Japanese Unexamined Patent Publication No. 2006-237559, for example).
The substrate treating unit carries out various types of treatment for substrates. The pod storage and transport unit is juxtaposed to the substrate treating unit for storing and transporting FOUPs (Front Opening Unified Pods) containing the substrates. The load port is juxtaposed to the pod storage and transport unit for receiving the FOUPs. The FOUPS are transferred to and from the load port by automatic guided vehicles (AGV), which constitute an automated material handling system, or an overhead hoist transfer. The plurality of (e.g. 16) racks in the pod storage and transport unit are provided for storing the FOUPs. The internal receiver is disposed between the pod storage and transport unit and the plurality of racks for receiving the FOUPs. The first transport device transports the FOUPs between the load port and racks. The second transport device transports the FOUPs between the racks and internal receiver.
In the first apparatus constructed as described above, the first transport device transports the FOUPs between the load port and the racks, and the second transport device transports the FOUPs between the internal receiver and racks. Therefore, these transport operations can be carried out substantially in parallel. This improves the efficiency of transporting the FOUPs to improve the throughput of the substrate treating apparatus.
Generally, the automated material handling system is not stable due to variations in transporting time. This impedes improvement in the throughput of the substrate treating apparatus. Then, a second apparatus has been proposed, which includes an increased number of load ports in order to absorb the variations (see Japanese Patent No. 3521330, for example). A third apparatus proposed has overhead hoist transfers in two lanes (see Japanese Unexamined Patent Publication No. 2010-192855, for example).
However, the conventional examples with such constructions have the following problems.
Since, generally, the substrate treating unit carries out treatment based on chemical reactions, and it is impossible to shorten treating time in the substrate treating unit. Therefore, in order to improve throughput, the number of treating tanks arranged in the substrate treating unit has to be increased to increase the number of treatments carried out in parallel. This will increase the number of empty FOUPs having contained substrates under treatment now, which will increase also repositories for the FOUPs. The first conventional apparatus has to be increased in width or height in order to increase the number of racks while allowing access thereto by both the first transport device and second transport device. However, an increased width of the apparatus will result in a reduced number of apparatus that can be arranged in a clean room. An increased height of the apparatus will impose restrictions on arrangement in connection with the ceiling height of the clean room. Thus, there is a problem that performance of high throughput cannot be maximized.
The second apparatus, with the increased load ports, has an enlarged frontage which is a disadvantage in the number of apparatus that can be arranged in a clean room.
The third apparatus has a disadvantage in terms of cost since the overhead hoist transfer vehicles are expensive. Further, the two lanes require an increased width between the load ports and an increased length of the apparatus. Thus, the third apparatus also has a disadvantage in the number of apparatus installed.